A Pilot Study of Switch to Lopinavir/Ritonavir (LPV/r) Monotherapy from Nonnucleoside Reverse Transcriptase Inhibitor–Based Therapy

Evaluation of four tenofovir-containing regimens as first-line treatments in Cameroon and Senegal: the ANRS 12115 DAYANA Trial

BACKGROUND

The aim of the present study was to determine appropriate tenofovir-based regimens meriting evaluation in large-scale randomized trials among sub-Saharan African patients.

METHODS

This was a randomized open-label 96-week prospective pilot study evaluating four first-line regimens: tenofovir/emtricitabine/nevirapine (group 1), tenofovir/lopinavir/ritonavir (group 2), tenofovir/emtricitabine/zidovudine (group 3) and tenofovir/emtricitabine/efavirenz (group 4) in antiretroviral-naive, HIV-1-infected patients in Senegal and Cameroon. The primary end point was defined as an HIV-1 RNA viral load <50 copies/ml (study detection limit) at week 16 in ≥50% of patients using intention-to-treat analysis.

RESULTS

At baseline, 119 patients included were 34% male, had a median plasma viral load of 5.4 log10 copies/ml and median CD4(+) T-cell count of 200 cells/mm(3) (range 53-358). The primary end point was achieved for groups 1, 3 and 4 (58% [n=31], 62% [n=29] and 53% [n=30], respectively), but not for group 2 (38% [n=29]). At week 96, undetectable HIV-1 RNA had been achieved in 74% of patients in group 1, 38% in group 2, 72% in group 3 and 73% in group 4. Patients with detectable HIV-1 RNA at week 16 were more likely to have baseline HIV-1 RNA≥100,000 copies/ml (adjusted OR 5.56, 95% CI 1.72, 16.67). HIV mutations associated with protease inhibitor resistance emerged in three patients, all of whom were in group 2. Anaemia occurred in two group 3 patients and was the only serious treatment-related adverse event.

CONCLUSIONS

Three efficient and safe tenofovir-based triple regimens were identified; the two-drug regimen (tenofovir/lopinavir/ritonavir) did not achieve the protocol-defined virological threshold of efficacy.

Effectiveness of protease inhibitor monotherapy versus combination antiretroviral maintenance therapy: a meta-analysis

BACKGROUND

The unparalleled success of combination antiretroviral therapy (cART) is based on the combination of three drugs from two classes. There is insufficient evidence whether simplification to ritonavir boosted protease inhibitor (PI/r) monotherapy in virologically suppressed HIV-infected patients is effective and safe to reduce cART side effects and costs.

METHODS

We systematically searched Medline, Embase, the Cochrane Library, conference proceedings and trial registries to identify all randomised controlled trials comparing PI/r monotherapy to cART in suppressed patients. We calculated in an intention to treat (loss-of follow-up, discontinuation of assigned drugs equals failure) and per-protocol analysis (exclusion of protocol violators following randomisation) and based on three different definitions for virological failure pooled risk ratios for remaining virologically suppressed.

FINDINGS

We identified 10 trials comparing 3 different PIs with cART based on a PI/r plus 2 reverse transcriptase inhibitors in 1189 patients. With the most conservative approach (viral load <50 copies/ml on two consecutive measurements), the risk ratios for viral suppression at 48 weeks of PI/r monotherapy compared to cART were in the ITT analysis 0.94 8 (95% CI 0.89 to 1.00) p = 0.06; risk difference -0.06 (95%CI -0.11 to 0) p = 0.05, p for heterogeneity  = 0.08, I(2) = 43.1%) and in the PP analysis 0.93 ((95%CI 0.90 to 0.97) p<0.001; risk difference -0.07 (95%CI -0.10 to -0.03) p<0.001, p for heterogeneity  = 0.44, I(2) = 0%). Reintroduction of cART in 44 patients with virological failure led in 93% to de-novo viral suppression.

INTERPRETATION

Virologically well suppressed HIV-infected patients have a lower chance to maintain viral suppression when switching from cART to PI/r monotherapy. Failing patients achieve high rates of de-novo viral suppression following reintroduction of reverse transcriptase inhibitors.

Patient Characteristics and Treatment Outcome Associated with Protease Inhibitor (PI) use in the Asia-Pacific Region

OBJECTIVES: Regimens containing protease inhibitors (PI) are less commonly used in developing countries due to high cost and less availability. We evaluated characteristics of patients initiating PI-based therapy according to previous antiretroviral (ARV) exposure; factors associated with initiating a PI-containing regimen using newer versus older PIs, and proportion of patients with detectable viral loads (VL) after initiating a PI-based regimen. METHODS: This analysis includes all patients who have initiated a PI-based regimen. ARV exposure was categorised: naïve (no previous ARV), 1st, 2nd, >/= 3rd switches; a switch was defined as starting or stopping any drug in a regimen. Newer PIs were defined as those approved by the US FDA after 1 January 2000. Detectable VL at 12 months was defined as VL >/= 400 copies/mL. Characteristics at PI initiation were evaluated. Logistic regression was used to determine factors associated with initiating a newer PI and detectable VL at 12 months after PI initiation. RESULTS: 1106 patients initiated PI-based therapy; of these, 618 (56%) were naïve patients. Overall, 22% (176) of patients had detectable VL at 12 months following the PI initiation. Being from a high income country (vs. mid/low income, OR = 1.80, p = 0.034) were more likely to be associated with detectable VL. CONCLUSION: The use of PIs in this cohort is dictated by accessibility and affordability issues particularly for the newer PIs. Short-term virological outcomes following PI-therapy in our cohort were good, and were associated with CD4 count at time of initiation.

[Lopinavir/ritonavir monotherapy as a simplification strategy in the treatment of HIV-1 infection]

Simplification of triple antiretroviral therapy to lopinavir/ritonavir (LPV/r) monotherapy in patients with well-controlled viremia for prolonged periods (more than 6 months) without prior failure with a protease inhibitor has been proposed as a strategy that could reduce the toxicity and costs of antiretroviral therapy in the long term while also preserving other therapeutic options. The results of several studies are currently available, some of which had a large number of patients and follow-up of up to 4 years. These studies indicate that this strategy is safe and efficacious, thus allowing its clinical use when indicated. This strategy may be especially useful in reducing the costs of treatment in countries with scarce economic resources. The role of LPV/r monotherapy in the prevention and management of lipodystrophy and in improving the selection of patients with an optimal risk-benefit ratio remains to be defined.

[Prognostic factors of virological response in patients treated with lopinavir/ritonavir monotherapy]

Nine clinical trials have analyzed whether the use of lopinavir-ritonavir (LPV/r) monotherapy could be a valid alternative to triple antiretroviral therapy. Four of these clinical trials included an analysis of risk factors for virological failure. The MONARK study evaluated monotherapy in treatment-naïve patients. The M03-613 trial evaluated monotherapy after a period of induction therapy with triple combination antiretroviral therapy. The study by Sprinz et al and the OK studies evaluated monotherapy as maintenance of virological suppression. The efficacy of monotherapy varied according to the scenario. In the scenario of induction-maintenance, the factors related to virological failure were suboptimal adherence and low baseline CD4 counts. In the scenario of maintenance, the factors related to virological failure were suboptimal adherence, nadir CD4 count and low hemoglobin. In treatment-naive patients, the risk of virological failure increased in patients who did not achieve a viral load of less than 400 copies/ml 4 weeks after initiating treatment and in those infected with non-B subtypes (a factor that was probably also related to suboptimal adherence).

[Lopinavir/ritonavir monotherapy for the treatment of HIV-1 infection: the emergence of resistance]

Treatment with lopinavir/ritonavir (LPV/r) monotherapy has been shown to be an effective alternative, especially in the maintenance of patients previously treated with combination therapy and prolonged virological suppression. LPV/r monotherapy is associated with a greater number of low-level viremia episodes than combination therapy, without resistance mutations being detected in the majority of patients. The incidence of the development of major resistance mutations in the OK pilot and OK04 studies was very low: 0.51 per 100 patients-year, and was mainly related to mutations in positions 46, 54 and 82, which have not compromised other therapeutic options. The contribution of low-level resistance mutations to loss of virological control seems small, and no different from that observed in combination therapy. However, this phenomenon should be studied in larger, long-term trials.

Regimen simplification to atazanavir-ritonavir alone as maintenance antiretroviral therapy: final 48-week clinical and virologic outcomes

BACKGROUND

Simplified maintenance therapy with ritonavir-boosted atazanavir (ATV/RTV) alone is attractive because of nucleoside reverse-transcriptase inhibitor (NRTI)-sparing benefits, low pill burden, once-daily dosage, and safety.

METHODS

Subjects with virologic suppression after > or = 48 weeks of initial antiretroviral therapy with 2 NRTIs and a protease inhibitor (PI) were enrolled. Subjects switched to ATV/RTV at entry and discontinued NRTIs after 6 weeks. The primary end point was time to virologic failure (confirmed HIV-1 RNA level > or = 200 copies/mL). Drug resistance at virologic failure was evaluated by standard genotyping and single-genome sequencing (SGS). Residual viremia (1.1-49 copies/mL) was measured by single-copy assay.

RESULTS

Thirty-four subjects simplified to ATV/RTV alone, of whom 30 (88%) did not experience virologic failure by 48 weeks after simplification. Residual viremia did not change significantly after NRTI discontinuation among those without virologic failure but did increase 4-12 weeks before confirmed virologic failure. No major PI-resistance mutations were identified at virologic failure by standard genotyping or SGS.

CONCLUSIONS

In this pilot study, simplified maintenance therapy with ATV/RTV alone maintained viral suppression in most subjects through 48 weeks. PI resistance was not detected among subjects experiencing virologic failure. Larger, randomized trials are warranted to further define the efficacy and safety of this strategy.

Predictors of loss of virologic response in subjects who simplified to lopinavir/ritonavir monotherapy from lopinavir/ritonavir plus zidovudine/lamivudine

Previous studies have demonstrated that lopinavir/ritonavir monotherapy maintained plasma HIV-1 RNA suppression in a large proportion of antiretroviral naive subjects. However, more subjects receiving lopinavir/ritonavir monotherapy experienced confirmed virologic rebound >50 copies/ml compared to a standard three-drug HAART regimen. In this study, we sought to determine the factors associated with maintenance of virologic suppression in subjects receiving lopinavir/ritonavir monotherapy. Antiretroviral-naive HIV-1-infected volunteers were randomized 2:1 to initiate a lopinavir/ritonavir-based combination regimen followed by simplification to lopinavir/ritonavir monotherapy or an efavirenz-based triple combination therapy and followed for 96 weeks. Potential predictors of time to loss of virologic response included baseline demographics, baseline HIV-1 RNA levels, baseline CD4(+) T cell counts, adherence as determined by 4-day subject recall, duration of HIV-1 RNA <50 copies/ml prior to simplification, and lopinavir concentrations. By the Cox proportional hazards model, higher reported adherence levels and higher baseline CD4(+) T cell counts were associated with a greater likelihood of maintaining virologic suppression while receiving lopinavir/ritonavir monotherapy. Lopinavir concentrations, including trough concentrations, were not significantly associated with virologic outcomes. This analysis suggests that adherence and higher baseline CD4(+) T cell counts may help to predict who will sustain virologic suppression with lopinavir/ritonavir monotherapy. The data also suggest that measuring lopinavir concentrations is not useful in predicting virologic response in these patients.

HIV monotherapy with ritonavir-boosted protease inhibitors: a systematic review

OBJECTIVE

To assess the efficacy of ritonavir-boosted protease inhibitor monotherapy.

DESIGN AND METHODS

Systematic review of all protease inhibitor-monotherapy studies published in peer-reviewed journals or presented at conferences to date. Data of randomized controlled trials were pooled to yield common odds ratios.

RESULTS

Twenty-two protease inhibitor-monotherapy studies were identified. In the intent-to-treat analysis, 395 out of 582 (67.9%) patients had undetectable HIV-RNA at the end of follow-up. In the six randomized controlled trials (all lopinavir/ritonavir monotherapy), the risk of therapy failure was greater on monotherapy: 121 out of 364 (33.2%) patients on monotherapy against 64 out of 280 (22.9%) patients on HAART [pooled odds ratio 1.48 (95% confidence interval 1.02-2.13, P = 0.037)]. Regarding patients with successfully resuppressed HIV-RNA upon (re-)introducing nucleoside reverse transcriptase inhibitors (NRTIs) as nonfailures, the risk of therapy failure was comparable: 98 out of 364 (26.9%) against 64 out of 280 (22.9%) patients [odds ratio 1.05 (95% confidence interval 0.72-1.53, P = 0.81)].

CONCLUSION

The overall efficacy of ritonavir-boosted protease inhibitor monotherapy is inferior to HAART. The efficacy improves in patients started on monotherapy after suppressed HIV-RNA for at least 6 months. Ten percent of patients have viral rebound with HIV-RNA levels between 50 and 500 copies/ml. Possible explanations are lack of HIV suppression in particular cells or compartments, alternative resistance mechanisms, and nonadherence. Once proven that reintroduction of NRTIs, in patients with loss of viral suppression, is safe and effective, a broader use of simplification of HAART to protease inhibitor monotherapy might be justified. This review supports that the majority of patients with prolonged viral suppression on HAART can successfully be treated with protease inhibitor monotherapy. Arguments for this strategy are NRTI/NNRTI side effects, NRTI/NNRTI resistance, and costs.

Simplification Strategies to Reduce Antiretroviral drug Exposure: Progress and Prospects

Current US guidelines for initial therapy of HIV type-1 (HIV-1) infection recommend daily, lifelong treatment with a combination of three antiretroviral drugs consisting of two nucleoside analogue reverse transcriptase inhibitors and a non-nucleoside reverse transcriptase inhibitor or a protease inhibitor. Although this approach has been successful in reducing morbidity and mortality from HIV-1 infection, concerns remain about adverse events from chronic drug exposure, the requirement for daily medication adherence, the risk of HIV-1 drug resistance and high treatment costs. The availability of antiretrovirals that are coformulated and dosed once daily have reduced pill burden and have simplified dosing schedules, but have not lowered drug exposure or cost. These limitations have stimulated research into drug-sparing strategies including intermittent therapy and simplified maintenance regimens. Randomized clinical trials have shown greater mortality with intermittent therapy compared with continuous therapy leading to rejection of this strategy. Pilot studies of simplified maintenance therapy with a ritonavir-boosted protease inhibitor alone have shown more promise, although concerns remain. This article reviews progress in the simplification of antiretroviral therapy, recent clinical trial results and prospects for the future.

A 96-week comparison of lopinavir-ritonavir combination therapy followed by lopinavir-ritonavir monotherapy versus efavirenz combination therapy

Antiretroviral-naive HIV-1-infected volunteers received zidovudine/lamivudine plus either lopinavir/ritonavir (n=104) or efavirenz (n=51). Lopinavir/ritonavir-treated subjects demonstrating 3 consecutive monthly HIV-1 RNA levels <50 copies/mL started lopinavir/ritonavir monotherapy. In previous-failure=failure analysis, 48% (lopinavir/ritonavir) and 61% (efavirenz) maintained HIV-1 RNA at <50 copies/mL through week 96, (P= .17; 95% confidence interval [CI] for the difference, -29% to 4%); in noncompletion=failure analysis, 60% (lopinavir/ritonavir) and 63% (efavirenz) maintained HIV-1 RNA at <50 copies/mL at week 96 (P= .73; 95% CI for the difference, -19% to 13%). Significant sparing of peripheral lipoatrophy was noted in the lopinavir/ritonavir simplification strategy. This study has provided important information for future studies using treatment simplified to lopinavir/ritonavir monotherapy.

Potential risks and benefits of HIV treatment simplification: a simulation model of a proposed clinical trial

BACKGROUND

In recent studies, subjects who had achieved suppression of the human immunodeficiency virus (HIV) RNA level while receiving an initial 3-drug antiretroviral regimen successfully maintained suppression while receiving treatment with a "boosted" protease inhibitor (PI) alone. We projected the long-term outcomes of this treatment simplification strategy to inform the design of a proposed multicenter, randomized clinical trial.

METHODS

We used published studies to estimate the efficacy, adverse effects, and cost of a sequence of HIV drug regimens for the simplification strategy, compared with those outcomes for the current standard-of-care (SOC) strategy. Using a published simulation model of HIV disease, we projected life expectancy, discounted quality-adjusted life expectancy (QALE), and discounted lifetime medical costs for each strategy.

RESULTS

Subjects who have not developed PI-resistant HIV infection at the time of failure of the simplification regimen have a greater life expectancy (27.9 vs. 27.1 years) and QALE (14.9 vs. 14.7 years), compared with SOC subjects, because they receive an additional line of therapy without negative consequences for future treatment options. The QALE for the simplification strategy remains higher than that for the SOC, unless a large proportion of patients experiencing virologic failure while receiving the simplification regimen develop PI resistance. Depending on the probability of simplification regimen failure, the advantage is maintained even if HIV develops PI resistance in 42%-70% of subjects. Projected lifetime costs are $26,500-$72,400 per person lower for the simplification strategy than for the SOC strategy.

CONCLUSIONS

An HIV treatment simplification strategy involving use of a boosted PI alone may lead to longer survival overall at lower cost, compared with the SOC combination therapy, because the simplification strategy potentially adds an additional line of therapy. The risk of emergence of PI resistance during treatment with a simplified regimen is a critical determinant of the viability of this strategy.